diff --git a/lighthouse-core/gather/driver.js b/lighthouse-core/gather/driver.js
index 5da3e6322294..9859907bb961 100644
--- a/lighthouse-core/gather/driver.js
+++ b/lighthouse-core/gather/driver.js
@@ -78,6 +78,13 @@ class Driver {
       // properties. See https://github.com/Microsoft/TypeScript/pull/22348.
       this._eventEmitter.emit(event.method, event.params);
     });
+
+    /**
+     * Used for monitoring network status events during gotoURL.
+     * @type {?LH.Crdp.Security.SecurityStateChangedEvent}
+     * @private
+     */
+    this._lastSecurityState = null;
   }
 
   static get traceCategories() {
@@ -876,6 +883,26 @@ class Driver {
     });
   }
 
+  async listenForSecurityStateChanges() {
+    this.on('Security.securityStateChanged', state => {
+      this._lastSecurityState = state;
+    });
+    await this.sendCommand('Security.enable');
+  }
+
+  /**
+   * @return {LH.Crdp.Security.SecurityStateChangedEvent}
+   */
+  getSecurityState() {
+    if (!this._lastSecurityState) {
+      // happens if 'listenForSecurityStateChanges' is not called,
+      // or if some assumptions about the Security domain are wrong
+      throw new Error('Expected a security state.');
+    }
+
+    return this._lastSecurityState;
+  }
+
   /**
    * @param {string} name The name of API whose permission you wish to query
    * @return {Promise<string>} The state of permissions, resolved in a promise.
diff --git a/lighthouse-core/gather/gather-runner.js b/lighthouse-core/gather/gather-runner.js
index 2d045fcf966e..003d334ad462 100644
--- a/lighthouse-core/gather/gather-runner.js
+++ b/lighthouse-core/gather/gather-runner.js
@@ -112,6 +112,7 @@ class GatherRunner {
     await driver.cacheNatives();
     await driver.registerPerformanceObserver();
     await driver.dismissJavaScriptDialogs();
+    await driver.listenForSecurityStateChanges();
     if (resetStorage) await driver.clearDataForOrigin(options.requestedUrl);
   }
 
@@ -172,6 +173,22 @@ class GatherRunner {
     }
   }
 
+  /**
+   * Throws an error if the security state is insecure.
+   * @param {LH.Crdp.Security.SecurityStateChangedEvent} securityState
+   * @throws {LHError}
+   */
+  static assertNoSecurityIssues({securityState, explanations}) {
+    if (securityState === 'insecure') {
+      const errorDef = {...LHError.errors.INSECURE_DOCUMENT_REQUEST};
+      const insecureDescriptions = explanations
+        .filter(exp => exp.securityState === 'insecure')
+        .map(exp => exp.description);
+      errorDef.message += ` ${insecureDescriptions.join(' ')}`;
+      throw new LHError(errorDef);
+    }
+  }
+
   /**
    * Navigates to about:blank and calls beforePass() on gatherers before tracing
    * has started and before navigation to the target page.
@@ -280,6 +297,8 @@ class GatherRunner {
       passContext.LighthouseRunWarnings.push(pageLoadError.friendlyMessage);
     }
 
+    this.assertNoSecurityIssues(driver.getSecurityState());
+
     // Expose devtoolsLog, networkRecords, and trace (if present) to gatherers
     /** @type {LH.Gatherer.LoadData} */
     const passData = {
diff --git a/lighthouse-core/lib/lh-error.js b/lighthouse-core/lib/lh-error.js
index 557fcc746d53..ae1d8dbf3646 100644
--- a/lighthouse-core/lib/lh-error.js
+++ b/lighthouse-core/lib/lh-error.js
@@ -142,6 +142,12 @@ const ERRORS = {
     message: strings.pageLoadFailed,
     lhrRuntimeError: true,
   },
+  /* Used when security error prevents page load. */
+  INSECURE_DOCUMENT_REQUEST: {
+    code: 'INSECURE_DOCUMENT_REQUEST',
+    message: strings.pageLoadFailedInsecure,
+    lhrRuntimeError: true,
+  },
 
   // Protocol internal failures
   TRACING_ALREADY_STARTED: {
diff --git a/lighthouse-core/lib/strings.js b/lighthouse-core/lib/strings.js
index 24bf4d91cd71..0b5c81edc013 100644
--- a/lighthouse-core/lib/strings.js
+++ b/lighthouse-core/lib/strings.js
@@ -11,6 +11,7 @@ module.exports = {
   badTraceRecording: `Something went wrong with recording the trace over your page load. Please run Lighthouse again.`,
   pageLoadTookTooLong: `Your page took too long to load. Please follow the opportunities in the report to reduce your page load time, and then try re-running Lighthouse.`,
   pageLoadFailed: `Lighthouse was unable to reliably load the page you requested. Make sure you are testing the correct URL and that the server is properly responding to all requests.`,
+  pageLoadFailedInsecure: `The URL you have provided does not have valid security credentials.`,
   internalChromeError: `An internal Chrome error occurred. Please restart Chrome and try re-running Lighthouse.`,
   requestContentTimeout: 'Fetching resource content has exceeded the allotted time',
   urlInvalid: `The URL you have provided appears to be invalid.`,
diff --git a/lighthouse-core/test/gather/fake-driver.js b/lighthouse-core/test/gather/fake-driver.js
index f90ed3b0f032..75ce1e2f3eca 100644
--- a/lighthouse-core/test/gather/fake-driver.js
+++ b/lighthouse-core/test/gather/fake-driver.js
@@ -81,6 +81,14 @@ const fakeDriver = {
   setExtraHTTPHeaders() {
     return Promise.resolve();
   },
+  listenForSecurityStateChanges() {
+    return Promise.resolve();
+  },
+  getSecurityState() {
+    return Promise.resolve({
+      securityState: 'secure',
+    });
+  },
 };
 
 module.exports = fakeDriver;
diff --git a/lighthouse-core/test/gather/gather-runner-test.js b/lighthouse-core/test/gather/gather-runner-test.js
index 8ab6da53e655..2e2d2443d4e7 100644
--- a/lighthouse-core/test/gather/gather-runner-test.js
+++ b/lighthouse-core/test/gather/gather-runner-test.js
@@ -321,6 +321,7 @@ describe('GatherRunner', function() {
       clearDataForOrigin: createCheck('calledClearStorage'),
       blockUrlPatterns: asyncFunc,
       setExtraHTTPHeaders: asyncFunc,
+      listenForSecurityStateChanges: asyncFunc,
     };
 
     return GatherRunner.setupDriver(driver, {settings: {}}).then(_ => {
@@ -379,6 +380,7 @@ describe('GatherRunner', function() {
       clearDataForOrigin: createCheck('calledClearStorage'),
       blockUrlPatterns: asyncFunc,
       setExtraHTTPHeaders: asyncFunc,
+      listenForSecurityStateChanges: asyncFunc,
     };
 
     return GatherRunner.setupDriver(driver, {
@@ -543,9 +545,9 @@ describe('GatherRunner', function() {
       ],
     };
 
-    return GatherRunner.afterPass({url, driver, passConfig}, {TestGatherer: []}).then(vals => {
+    return GatherRunner.afterPass({url, driver, passConfig}, {TestGatherer: []}).then(passData => {
       assert.equal(calledDevtoolsLogCollect, true);
-      assert.strictEqual(vals.devtoolsLog[0], fakeDevtoolsMessage);
+      assert.strictEqual(passData.devtoolsLog[0], fakeDevtoolsMessage);
     });
   });
 
@@ -647,6 +649,7 @@ describe('GatherRunner', function() {
       mainRecord.localizedFailDescription = 'foobar';
       const error = GatherRunner.getPageLoadError(url, [mainRecord]);
       assert.equal(error.message, 'FAILED_DOCUMENT_REQUEST');
+      assert.equal(error.code, 'FAILED_DOCUMENT_REQUEST');
       assert.ok(/^Lighthouse was unable to reliably load/.test(error.friendlyMessage));
     });
 
@@ -655,6 +658,7 @@ describe('GatherRunner', function() {
       const records = [];
       const error = GatherRunner.getPageLoadError(url, records);
       assert.equal(error.message, 'NO_DOCUMENT_REQUEST');
+      assert.equal(error.code, 'NO_DOCUMENT_REQUEST');
       assert.ok(/^Lighthouse was unable to reliably load/.test(error.friendlyMessage));
     });
 
@@ -665,6 +669,7 @@ describe('GatherRunner', function() {
       mainRecord.statusCode = 404;
       const error = GatherRunner.getPageLoadError(url, [mainRecord]);
       assert.equal(error.message, 'ERRORED_DOCUMENT_REQUEST');
+      assert.equal(error.code, 'ERRORED_DOCUMENT_REQUEST');
       assert.ok(/^Lighthouse was unable to reliably load/.test(error.friendlyMessage));
     });
 
@@ -675,10 +680,49 @@ describe('GatherRunner', function() {
       mainRecord.statusCode = 500;
       const error = GatherRunner.getPageLoadError(url, [mainRecord]);
       assert.equal(error.message, 'ERRORED_DOCUMENT_REQUEST');
+      assert.equal(error.code, 'ERRORED_DOCUMENT_REQUEST');
       assert.ok(/^Lighthouse was unable to reliably load/.test(error.friendlyMessage));
     });
   });
 
+  describe('#assertNoSecurityIssues', () => {
+    it('succeeds when page is secure', () => {
+      const secureSecurityState = {
+        securityState: 'secure',
+      };
+      GatherRunner.assertNoSecurityIssues(secureSecurityState);
+    });
+
+    it('fails when page is insecure', () => {
+      const insecureSecurityState = {
+        explanations: [
+          {
+            description: 'reason 1.',
+            securityState: 'insecure',
+          },
+          {
+            description: 'blah.',
+            securityState: 'info',
+          },
+          {
+            description: 'reason 2.',
+            securityState: 'insecure',
+          },
+        ],
+        securityState: 'insecure',
+      };
+      try {
+        GatherRunner.assertNoSecurityIssues(insecureSecurityState);
+        assert.fail('expected INSECURE_DOCUMENT_REQUEST LHError');
+      } catch (err) {
+        assert.equal(err.message, 'INSECURE_DOCUMENT_REQUEST');
+        assert.equal(err.code, 'INSECURE_DOCUMENT_REQUEST');
+        /* eslint-disable-next-line max-len */
+        assert.equal(err.friendlyMessage, 'The URL you have provided does not have valid security credentials. reason 1. reason 2.');
+      }
+    });
+  });
+
   describe('artifact collection', () => {
     // Make sure our gatherers never execute in parallel
     it('runs gatherer lifecycle methods strictly in sequence', async () => {